This invention relates to a device for igniting fuel, comprising at least one burner, the device being fitted with ignition means. Such devices are used, for instance, in gas-fired heaters and heating boilers for CH systems. In reflector heaters in stables for breeding chickens or other animals, the ignition means are often absent. Such heating systems are often provided with a large number of burners, for instance to keep a large space at a uniformly distributed, constant temperature. Especially in that case, igniting all burners is a very serious problem.
A frequently used method to ignite a plurality of burners is to ignite each burner by hand. That is a highly time consuming job, so that, in view of the high labor costs involved, this is an expensive solution. Therefore, the burners, once they have been ignited by hand, are mostly set in a lowest operative mode in the periods that there is no heat requirement. This obviates the burners having to be re-ignited every time when the use of the burners is desired again. Keeping the burners in a lowest operative mode is cheap with regard to the labor costs, but expensive with regard to fuel consumption. Moreover, in the lowest operative mode of the burners, relatively much carbon monoxide is produced, which is harmful to animals or humans that are in the space to be heated.
One solution is to provide each burner with centrally controllable electronic ignition means. This has two disadvantages. In the first place, such a device depends on a power supply. If this power supply fails, this means that a burner which has gone out for whatever reason cannot be ignited anymore. This can inflict great damage in, for instance, a stable for breeding animals, where it is of vital importance that heat be available continuously to keep the temperature in the space constant. In the second place, this electronic solution is expensive because of the technically complicated measures it entails.
The present invention contemplates solving these problems. That is, the invention contemplates a device for igniting fuel, wherein the ignition means can ignite the burner without this requiring external electric energy to be supplied.
To that end, the invention provides a device of the type described in the preamble, which is characterized in that the ignition means comprise a movable element which is connected to a fluid line, such that a fluid contained in the fluid line, when it flows, creates a pressure difference across the movable element, as a result of which the movable element is set in motion, the movable element being connected with the ignition element, such that the movement of the movable element generates via the ignition element an ignition temperature by means of which the fuel is caused to combust, the fluid line being either a fuel line for the purpose of the supply of fuel to the at least one burner, or a fluid line through which flows a fluid to be heated by means of the at least one burner.
With such a device, therefore, a burner can be ignited by means of a movement which is generated by the kinetic energy of the fluid flowing. Accordingly, as soon as the fluid starts to flow, so that the movable element is energized, ignition of the burner will be effected. Accordingly, there is no necessity for supplying power to the device to ignite the burner. In the application involving the heating of stables, where a large number of burners are present, the connected burners can be readily ignited simultaneously by turning on the central gas inlet cock. The combustible gas then forms the fluid setting the movable element in motion.
According to a further elaboration of the invention, the ignition means comprise valve means and spring means which exert an oppositely directed spring force on the movable element with respect to the force as a result of the pressure difference, while in an opened position of the valve means the pressure difference across the movable element is smaller than in a closed position, while in said closed position the spring force is smaller than the force as a result of the pressure difference, while in the opened position of the valve means the spring force is greater than the force as a result of the pressure difference, such that upon a periodic alternation of the position of the valve means between the first and the second position, the movement of the movable element repeats itself.
The repetitive movement of the movable element provides repetitive attempts of the ignition means to ignite fuel in the burner or in an ignition burner that may be present. Such repetition of the ignition may be necessary when the first ignition attempt has failed, for instance in that fuel has flowed in too small an amount, or not far enough yet, into the burner, the optional ignition burner or a combustion chamber, and hence has not been ignited yet.
Preferably, the burner is provided with deactivation means which , when the fuel has been ignited or is burning, reduce the pressure difference across the movable element, such that the movable element stops moving. The reason is that it is not necessary for the ignition attempts to be repeated when the burner has already been ignited.
It is therefor recommended that the at least one burner is provided with a protection which, as a result of a termination of the combustion, shuts off a burner line through closing means, such that no fuel flows into the at least one burner, the protection being coupled to the ignition means, such that closing the burner line is accompanied by the development of a pressure difference across the movable element as a result of which the movable element is set in motion. Thus the protection prevents fuel, subsequent to the burner flame becoming erroneously extinguished, from leaving the burner unburned, thereby giving rise to a possibly explosion-dangerous situation in the space in which the burner is set up. Due to the protection setting the movable element in motion by creating the pressure difference of the fluid, the ignition means are activated. As a result, the extinguished burner will automatically be ignited again. Obviously, these ignition attempts no longer take place when the supply of fluid has been stopped, so that no flow of fluid across the movable element takes place anymore.
Preferably, the movable element is coupled to the closing means, such that as a result of the movement of the movable element the closing means are opened when the movement of the movable element generates the ignition temperature via the ignition element, so that fuel flows into the at least one burner. This guarantees that fuel flows into the burner at the moment of an ignition attempt.
According to a further elaboration of the invention, the ignition means comprise an ignition burner which, for instance, is ignited with a piezo element, a flint or a spark which is generated with a generator such as is present in a dyno torch. The piezo element, the flint or the generator in their turn are energized by the movable element. Once this ignition burner burns, the gas supply of the burner is subsequently activated. This can be effected in the same manner as in the conventional gas heaters, whereby with the aid of a thermocouple a gas valve is opened in the gas supply line of the burner. Such a thermocouple is set up in the flame of the ignition burner and generates a small current by means of which the valve referred to is operated. According to a further elaboration of the invention, it is preferred that the closing means also shut off the burner line for the ignition burner when the burner is extinguished for one reason or another.
In a preferred embodiment, the movable element is a membrane enclosed by a membrane housing, the membrane separating the membrane housing into two compartments, the compartments being connected with the fluid line, such that a fluid flowing through the fluid line fills at least one of the compartments and creates the pressure difference across the membrane as a result of which the membrane is set in motion. The valve means may be provided in the membrane and the membrane housing, while the valve means are substantially provided with an opening in the membrane which provides a fluid passage between the two compartments, a membrane valve on the opening in the membrane, and valve control means, such that the valve control means as a result of the movement of the membrane set the membrane valve alternately in the open and the closed position. This preferred embodiment is a reliable and effective embodiment of the invention. Due to the valve means being enclosed by a membrane housing, the chance of leakage of the fluid to an environment is strongly reduced.
The fluid may be the fuel. In that case, according to a further elaboration of the invention, the deactivation means of the at least one burner comprise substantially a pressure equalization line, the pressure equalization line connecting the downstream compartment of the membrane housing with the burner line of the burner, such that when the burner burns, the pressure difference across the membrane is reduced, so that the membrane stops moving. The pressure equalization line can be provided with a buffer tank and a check valve, such that when the membrane valve is in the closed position and fuel is supplied to the burner via the fluid line, the membrane, despite the pressure prevailing in the burner line, can still traverse its stroke completely in that the fuel in the downstream compartment of the membrane housing can flow to the buffer tank. This embodiment of the deactivation means is highly practical, simple and therefore inexpensive.
The fluid can also be a liquid, for instance water. The at least one burner may then be adapted to heat up the liquid by means of a heat exchanger, with the liquid flowing from the heat exchanger to the deactivation means, while the deactivation means comprise substantially temperature-controlled valve means and lines, the temperature-controlled valve means set themselves into a first position as a result of a particular rise of the temperature or at a particular first set value of the temperature of the liquid, the pressure difference across the movable element being reduced via the lines of the deactivation means, such that the movable element stops moving, while the temperature-controlled valve means, through a particular decrease of the temperature or upon a second set value of the temperatures being reached, set themselves into a second position, while the pressure difference across the movable element is increased, such that the movable element is set in motion. Thus that at least one burner can be ignited by allowing a fluid to flow, the fluid in this case not being the fuel. This embodiment of the invention can be used in, for instance, a CH installation or in a hot water for sanitary water.
In every embodiment of the invention, the fuel can be a combustible gas.
Each embodiment of the invention can be provided with more than one burner with associated ignition means. All burners that are provided with such an ignition device can be ignited at the same moment by applying a certain fluid pressure across the movable element. After some time, all or most burners will be ignited. In case of a defective burner, the repetitive ignition will then continue needlessly. That can be stopped by causing the fluid pressure to decrease, such that the movable element of this defective burner stops moving, while the fluid pressure still remains high enough for the other burners to keep burning.
It is noted that U.S. Pat. No. 3,562,562 discloses a device for igniting the burners of a gas cooker, in which a membrane pulsates and with this pulsating action energizes a piezoelectric element; however, the required fluid pressure for energizing the pulsating movement of the membrane is formed by a separate vacuum source which is present especially for this purpose. Maintaining a vacuum in most cases requires a vacuum pump, and hence electricity to drive this pump. In the present invention, by contrast, for the purpose of the ignition, use is made of the flow of a fluid that in any case is to be present already. To be considered here is the fuel that is to be burnt in the main burner, or a medium to be heated with the main burner, such as, for instance, sanitary water.
The invention will be further clarified on the basis of four exemplary embodiments which will be described hereinafter, with reference to the drawing.